Description of the Prior Art
Work lights of the type defined above are known, whereby the gas discharge lamp is operated on alternating current. The alternating current causes the light to flicker at substantially twice the supply frequency, which is very disturbing and in many cases fatiguing. Gas discharge lamps (fluorescent tubes) are known which contain, in the interior of the lamp, a layer of fluorescent material constructed as a storage element so that an afterglow effect is produced which partly dampens the flickering effect. The relatively thick afterglow layer, however, reduces the light output in some cases by up to 50%.
If gas discharge lamps operated on alternating current are used for room lighting, the flickering effect is less disturbing owing to the greater distance from the workplace.
It is further known to operate gas discharge lamps with high frequency voltage, for instance 35 kHz, in order to avoid flicker effects. Because of the high frequency voltage the flickering is no longer visible, however, disadvantageous biological effects are possible. For instance, X-rays could be present. It therefore becomes necessary to shield the gas discharge lamps and to provide filter elements for the supply circuits so that high frequency voltages do not cause disruptions in the supply lines.